I go to [http://www.pianoteq.com/free_addons] and if I mouseover every single download link I see that they are all the same, "http://www.pianoteq.com/download?file=" right down the list.  And every single one that's clicked just brings you to the user area.

Well, did you log in? Once you do, and reach the user area, the older instruments (the Erard, the Graff, etc) are found on the Downloads tab. All of them are included in the KIViR instruments ptq file, which can be downloaded at the bottom of that tab. (You do have to register before you can reach the page with the Download tab.)